FR3019303A1 - DEVICE FOR MEASURING AT LEAST ONE PHYSICAL SIZE OF AN ELECTRICAL INSTALLATION - Google Patents

Abstract

The invention relates to a measuring device (10) comprising a current sensor (20) and a measuring unit (40) connected together by a connection cable (50). This connection cable (50) comprises three pairs of conductors, including a first measurement pair (51) arranged to transmit a signal representative of the current measured by said sensor (20), a second pair of power supply (52) arranged to supply electrically said sensor (20) and said measuring unit (40), and a third communication pair (53) arranged to transmit at least one complementary signal between said sensor (20) and said measuring unit (40), such as an identification characteristic of said sensor enabling said measurement unit to recognize said sensor.

Description

DEVICE FOR MEASURING AT LEAST ONE PHYSICAL SIZE OF AN ELECTRICAL INSTALLATION TECHNICAL FIELD The present invention relates to a device for measuring at least one physical quantity of an electrical installation, comprising at least one sensor arranged to measure at least said device. physical quantity and outputting at least one signal representative of said physical quantity, and at least one measurement unit arranged to receive said signal and process it to deliver at least one exploitable measurement value, said sensor and said measurement unit being connected to each other by at least one connecting cable. PRIOR ART: When setting up power measurement devices on an electrical installation, the configuration and verification phase of the installation is often a source of errors, in particular on three-phase networks. Indeed, this implementation requires to place current and / or voltage sensors on the conductors or phases of the electrical installation and connect these sensors to measurement units that can be deported. Consequently, errors in this phase of installation are mainly due to improper connection of the current measurement channels and voltage measurement channels between the sensors and the measuring units, to a sensor size declared as erroneous. polarity reversal of current sensors, etc. These errors are sometimes difficult to correct and may even, in some cases, go unnoticed for a while, which can lead to false measurement values and consequently to incorrect decisions in the management of the electrical installation.

In addition, the power measurement devices are more and more accurate while remaining reasonable in terms of cost. In contrast, precision current sensors remain expensive because they are based on expensive and bulky magnetic materials. By combining accurate calibration data with simple, inexpensive and inherently inaccurate current sensors, it is possible to achieve greater accuracy. However, these calibration data must be transmitted to the measuring device, otherwise the measured values will remain inaccurate. This constraint assumes a certain complexity of the current sensor, which necessarily induces an additional cost that is not always justified with regard to the application in question.

Finally, it may be useful to transmit additional information relating to the current and / or voltage sensors to the measurement unit or vice versa to enrich the functionalities of said sensors, for example, the temperature information of these sensors to increase the accuracy. measures, or any other additional information. Indeed, the temperature information can be used to compensate for the temperature but also to provide information on the environment of the sensor for example to generate an alarm if a critical temperature threshold is exceeded. .

However, at present there is no power measurement of an electrical installation, cheap current or voltage sensors, providing additional information to the measuring devices to which they are connected. Today, most measuring devices use current sensors in the form of current transformers with a secondary circuit in amperes, whose nominal value is 5A or 1A, without an integrated auxiliary sensor. There is a tendency to go to current transformers having a secondary circuit in voltage, the most commonly used value is 1 / 3V. This evolution makes it possible to lower the price of current transformers by reducing the size of the magnetic circuits, but brings no novelty in terms of functionality. The user must always configure the connected sensor type: current sensor or voltage sensor, as well as its calibration data. It can always be wrong polarity. And no additional function can be provided by this type of sensor. To correct branching errors, an analysis of the phase relationship between current and voltage is generally used. But this approach supposes the presence of a significant current and a prior knowledge of the power factor of the load. This connection correction can not be done easily before commissioning, even though electrical panels are often pre-wired before delivery. It would therefore be advantageous to be able to check that all the wiring has been correctly done before commissioning the electrical installation. The solutions currently available on the market are not totally satisfactory.

SUMMARY OF THE INVENTION The present invention aims at overcoming these disadvantages by proposing an intelligent, modular, economical measuring device, suitable for both simple and advanced sensors, with the aim of improving the quality and efficiency of precision of measurements, by making possible the automatic recognition of the sensors by the measuring devices, making it possible to check the correct functioning of the sensors and to avoid the transcription errors of the sensor size, the type of sensors, the wiring errors, as well as that fraud by detection of the absence of a particular sensor.

For this purpose, the invention relates to a measuring device of the kind indicated in the preamble, characterized in that said connection cable comprises at least three pairs of conductors, including a first pair of conductors, called measuring pair, arranged to transmit said signal representative of said physical quantity measured by said sensor, a second pair of conductors, called power pair, arranged to electrically power said sensor by said measurement unit, and a third pair of conductors, called communication pair, arranged to transmit at least one complementary signal between said sensor and said measurement unit allowing at least the automatic recognition of said sensor by said measurement unit, and in that said complementary signal transmitted on at least one of the conductors of said communication pair is indifferently a signal analog or digital. In a preferred embodiment, the device comprises encoding means arranged to characterize said sensor and transmit to said measurement unit via said communication pair at least one complementary signal corresponding to at least one identification characteristic of said sensor allowing said unit of measurement to automatically recognize said sensor.

Preferably, the sensor comprises two resistors whose resistance values are chosen as a function of at least one identification characteristic of said sensor. In this case, the measuring unit comprises two other resistors arranged to form, with the two resistors of said sensor, two dividing bridges connected on the one hand to said pair of power supplies and on the other hand to said pair of communication elements for delivering to the terminals of said communication pair at least one analog voltage complementary signal representative of said identification characteristic of said sensor. The sensor may comprise a processing unit in which at least one identifying characteristic of said sensor is recorded, this processing unit being connected on the one hand to said pair of power supplies and on the other hand to at least one of the drivers of the sensor. the communication pair for supplying at least one complementary signal in digital form representative of said identification characteristic of said sensor. The encoding means may be arranged to transmit to said measurement unit via said communication pair a plurality of complementary signals corresponding to a plurality of identification characteristics of said sensor enabling said measurement unit to recognize said sensor, which identification characteristics can be selected from the group consisting of the nominal voltage of the sensor, the nominal current of the sensor, the calibration data of the sensor, the compensation curve of the cap gain errors the compensation curve of the phase errors of the sensor. The communication pair may be arranged to convey on one of its conductors at least a first complementary signal representative of at least one identification characteristic of said sensor and on the other of its conductors at least a second complementary signal corresponding to an auxiliary physical quantity of said electrical installation.

In a preferred manner, the sensor is a current sensor arranged to measure the current on one of the conductors of said electrical installation. In a first variant embodiment, the measuring device may comprise at least one auxiliary voltage sensor arranged to measure an auxiliary voltage value representative of the voltage present on the conductor whose current is measured by said current sensor, this value of auxiliary voltage forming an auxiliary physical quantity conveyed on one of the conductors of said communication pair.

This auxiliary voltage sensor can be integrated in said current sensor or connected in series between said current sensor and said measurement unit and connected to each of them by at least one connection cable.

This auxiliary voltage sensor may comprise at least one selector arranged to automatically reverse the direction of connection of said auxiliary voltage sensor between said current sensor and said measurement unit in the event of a connection error.

In a second variant embodiment, the current sensor may comprise at least one earth leakage current sensor at a very low frequency with respect to the frequency of the network supplying said electrical installation, arranged to measure a leakage current value at the earth with a bandwidth including at least the frequency of the supply network, this earth leakage current value forming an auxiliary physical quantity conveyed on one of the conductors of said pair of communication. In a third embodiment, the current sensor may comprise at least one temperature sensor arranged to measure the temperature of said current sensor, this temperature forming an auxiliary physical quantity conveyed on one of the conductors of said pair of communication. In a fourth variant embodiment, the current sensor may comprise at least one additional current sensor arranged to perform a second measurement of current on the conductor of said electrical installation, this second current measurement forming a physical quantity conveyed on one of the conductors. said pair of communication to verify the proper operation of said current sensor by comparing this second current measurement with that performed by said current sensor.

Preferably, the measurement unit comprises a processing unit containing at least a table of correspondences between identification characteristics and sensors, and the processing unit is connected to said communication pair to receive at least the signal complementary representative of said identification feature enabling it to automatically recognize the sensor that is connected to said measurement unit and deliver a usable correlated value of said measured physical quantity. The measuring device advantageously comprises N current sensors, each provided with an auxiliary voltage sensor, and N voltage sensors arranged to respectively measure the current and the voltage on N conductors of said electrical installation. In this case, the measurement unit may comprise a correlation module arranged to match the voltage measurement which corresponds to the measurement of the auxiliary voltage performed on the same conductor of said electrical installation and automatically compensate for any connection errors. said sensors. The object of the invention is also achieved by the use of the measuring device described above to detect an attempt at fraud on said measuring device by detecting an inconsistency on the signals transmitted via said connection cable between said sensor and said unit of measure. The object of the invention is also achieved by the use of the measuring device for detecting the opening of a cut-off device arranged upstream of an electrical installation if on the one hand the voltage sensor is connected upstream of said switching device and if on the other hand the current sensor provided with its auxiliary voltage sensor is connected downstream of said cut-off device. Brief description of the drawings: The present invention and its advantages will appear better in the following description of several embodiments given by way of non-limiting example, with reference to the accompanying drawings, in which: - Figure 1 shows a first measuring device according to the invention provided with a simple current sensor with encoding made by two resistors disposed in said sensor, - Figure 2 shows a second measuring device according to the invention provided with an evolved current sensor in the form of an integrator on a Rogowski loop and an auxiliary voltage sensor in the form of a voltage detection electrode; - Figure 3 represents a third measuring device according to the invention provided with a separate auxiliary voltage sensor 4 represents a fourth measuring device according to the invention, similar to that of FIG. 3, but comprising a selector for making the auxiliary voltage sensor reversible; - FIG. 5 represents a measurement device according to the invention connected to a three-phase electrical installation showing a connection error between the voltage and current paths corresponding to the phases L2 and L3, and FIG. 6 is a diagram of the voltage signals of the three-phase installation of FIG. 5 and of the auxiliary voltage signal Vaux measured by the measuring device according to the invention provided with a correlation module automatically seeking the signaling channel. voltage corresponding best to the auxiliary voltage measured.

Illustrations of the invention and various ways of carrying it out: With reference to the figures, the measuring device 10-13 according to the invention comprises a sensor 20, 20 'arranged to measure at least one physical quantity of an electrical installation and a measuring unit 40 coupled to said sensor 20, 20 'by a particular connecting cable 50. The sensor is in the example described and illustrated a current sensor 20, 20 'arranged to measure the current on one of the conductors L1 of the electrical installation, but may relate to any other type of sensor. The current sensor 20, 20 'uses existing technologies, such as a current transformer, a Rogowski loop, sensors based on a magnetic field measurement such as the Hall effect or the "Fluxgate" system, or the like, and delivers a signal representative of the measured current, this signal being generally of analog form. The measurement unit 40 comprises in particular a processing unit 45, represented only in FIG. 1 but present in all the embodiments according to FIGS. 2 to 4. This processing unit 45 is programmable and is arranged to receive the signal coming from said current sensor 20, 20 '. The processing unit 45 furthermore makes it possible to process and exploit the signal in order to display a measurement value exploitable by an operator and / or a supervisory control unit that can be deported, such as a current value. , power, energy, a power factor, harmonic analysis of currents and / or powers, etc. The connection cable 50 used to connect the current sensor 20, 20 'and the measurement unit 40 is a modular cable that has six positions and six contacts, commonly known as RJ12 or any similar cable. This type of RJ12 cable, also called Registered Jack 12, is an international standard used by fixed telephone sets. It is also used in the field of local networks. It has three pairs of conductors 51, 52, 53. A first pair of conductors 51 is used for the differential transmission of an analog signal representative of a quantity to be measured from said current sensor 20, 20 ', is called by the following "measurement pair", and is connected to the processing unit 45. A second pair of conductors 52 is used for the supply of the sensor 20, 20 'by the measurement unit 40, and is called thereafter "Power pair". A third pair of conductors 53 is used to transmit complementary information DET1, DET2 between the current sensor 20, 20 'and the measurement unit 40, is hereinafter called "communication pair" and is connected to the unit. Of course, any other connection system having at least three pairs of conductors can be used. The conductors 51+, 51- of the measurement pair 51 are biased by the measurement unit 40 by means of two resistors 41, 42 of high value relative to the maximum output resistance of the current sensor 20, 20. . A first resistor 41 is connected between one of the conductors 51+ of the measurement pair 51 and the positive polarity conductor 52+ of the power supply pair 52, and the second resistor 42 is connected between the second conductor 51- of the pair. 51 and the negative-polarity conductor 52 of the supply pair 52. When no current sensor is connected to the measurement unit 40, the differential voltage on the measurement pair 51 is almost constant and adjacent to the voltage of the supply pair 52. When a current sensor 20, 20 'is connected, and because of the low output impedance of the current sensor 20, 20', the differential voltage on the pair of measure 51 is the image of the signal to be measured. Since the measuring device 10-13 is intended for the measurement of AC signals, the measurement of the average value of this differential voltage signal consequently makes it possible to detect the presence of a current sensor 20, 20 '.

FIG. 1 illustrates a first embodiment of the measuring device 10 according to the invention comprising a simple passive current sensor 20 constituted by a current transformer, whose primary circuit 21 is formed by the driver L1 of the electrical installation to be controlled and the secondary circuit 22 is coupled to the measurement pair 51. This measuring device 10 comprises encoding means of said current sensor 20. For this purpose, the communication pair 53 is used to form two bridges voltage dividers by means of two pairs of resistors 23, 24 and 25, 26, respectively present in the current sensor 20 and in the measurement unit 40. Preferably, but not exclusively, on each conductor 53a, 53b of this communication pair 53, a resistor 25, 26 located in the measurement unit 40 between the conductor 53a, 53b and the positive polarity 52+ of the supply pair 52 and a resistor 23, 24 located in the current sensor 20 between the conductor 53a, 53b and the negative polarity 52- of the supply pair 52. Thus, the value of the voltage between each conductor 53a, 53b and the negative polarity conductor 52- Conductor 52+ of positive polarity of the supply voltage depends on the value of the resistors 23-26 forming the two dividing bridges and to a certain extent the resistance of the conductors 53a, 53b of the communication pair 53. free from the influence of the conductors 53a, 53b by using for the resistors 23-26 high values, typically from a few kOhms to a few tens of kOhms, with respect to the resistances of the conductors 53a, 53b, typically from a few fractions of Ohms to a few dozen ohms. This voltage on the conductors 53a, 53b of the communication pair 53 is converted into a digital value by means of an analog / digital converter (not shown) integrated in the processing unit 45 of the measurement unit 40. In this way, it is possible to encode about twenty voltage levels on each of the two conductors 53a, 53b of the communication pair 53, ie about four hundred different voltage values available, thus offering a plurality of codes for characterizing A current sensor 20. Of course, the more different levels are chosen, the higher the coding richness, but the greater the sensitivity to disturbances and to the length of the cables. Preferably, these voltage levels are distributed between OV and the supply voltage to provide maximum immunity to disturbances. This encoding method makes it possible to non-exhaustively include the nominal size of the current sensor 20 by choosing the value of the resistors 23, 24 as a function of said rating. Given the relatively small number of calibres to be encoded, or between ten and thirty current sensor calibres useful for covering the needs of the market, one can also use the relatively high number of encoding possibilities to identify other information such as compensation curve typical of gain and phase errors by current sensor model. One can imagine for the same caliber of current sensor, several manufacturing technologies, depending on the desired performance. An Iron / Silicon core current transformer will be cheaper than a similar Iron / Nickel core transformer but will also be less accurate. The compensation curve to be applied is not only a function of the size, but also of the chosen technology. The processing unit 45 is programmable and notably comprises a table of correspondences between identification characteristics and current sensors 20, 20 'making it possible to correlate with the complementary signals that it receives via the communication pair 53. to automatically recognize the type of current sensor 20, 20 'connected to said measurement unit 40 and thus to deliver a readable correlated value of the physical quantity measured by said current sensor 20, 20'. FIG. 2 illustrates a second embodiment of the measuring device 11 according to the invention provided with an advanced current sensor 20 'comprising a Rogowski loop 27 traversed by the conductor L1 of the electrical installation to be tested, and associated with an integrator 28, whose outputs are connected to the conductors 51+, 51- of the measurement pair 51 connected to the processing unit 45 (not shown in this figure). In this embodiment, an auxiliary voltage sensor 30 is integrated in the current sensor 20 'and arranged to measure an auxiliary voltage value image of the driver voltage L1 of the electrical installation on which the current sensor 20, 20 'is installed, using existing technologies, such as capacitive measurement, electric field measurement, resistive measurement, or the like, and to provide a signal representative of the measured voltage, which signal is generally of analog form. The illustrated auxiliary voltage sensor 30 uses a capacitive measurement by means of a non-contact voltage sensing electrode 31 disposed near the conductor L1 of said installation, associated with a capacitor 33 connected to the negative conductor 52- of the pair. power supply 52 and an amplifier 32 connected to one of the conductors 53b of the communication pair 53 for transmitting a signal representative of the measured voltage, this signal being generally of analog form. In this embodiment, the resistors 23, 24 making it possible to characterize the current sensor 20 of the previous example, are replaced by a processing unit 60, typically a programmable microcontroller, powered by the conductors 52+, 52- of the supply pair 52. This processing unit 60 is used to transmit on one of the conductors 53a of the communication pair 53 complementary signals in digital form corresponding to identification characteristics of the current sensor 20 'connected to the unit. The identification features may be nominal rating information, a serial number, and calibration data for accurate compensation of gain and phase errors due to the current sensor 20 'as such. nor by model of current sensor, as in the previous example. This processing unit 60 also makes it possible to transmit additional interesting information such as the temperature of the current sensor 20 'and the auxiliary voltage sensor 30 for example. In this case, it is necessary to add in the current sensor 20, 20 'a temperature sensor. When the current sensor 20 'consists of a Rogowski loop 27 associated with its integrator 28, as is the case in FIG. 2, it is known that it is very difficult to guarantee accuracy and reproducibility by construction. this type of current sensor, because of mechanical tolerances and tolerances on component values. On the other hand, it is also known that it is relatively easy to measure these errors and then record them in the processing unit 60 of the current sensor 20 'in order to take them into account during the measurements and to compensate or correct measurements in result. FIG. 3 illustrates a third embodiment of the measuring device 12 according to the invention provided with an auxiliary voltage sensor 30 separate from the current sensor, which may be either a simple current sensor 20 according to FIG. 20 'evolved current according to Figure 2. In this case, the auxiliary voltage sensor 30 is connected in series between the current sensor 20, 20' and the measurement unit 40 by means of two connection cables 50 six positions .

Figure 4 illustrates a fourth embodiment of the measuring device 13 according to the invention, similar to that of Figure 3, but having a selector 70 to make the auxiliary voltage sensor 30 reversible automatically simplified the work of the operator. Since the auxiliary voltage sensor 30 is connected between the current sensor 20, 20 'and the measurement unit 40, the operator can err on the branching direction since the plugs of the connection cables 50 are identical.

The processing unit 60 provided in the auxiliary voltage sensor 30 is arranged to detect the direction of the connection and automatically switch the selector 70 to reverse the direction of connection in case of connection error.

The measuring device 10-13 as just described has intelligent functions. In particular, it is able to differentiate a simple current sensor 20 whose encoding of the type of current sensor is made by resistors 23, 24, of a digital linkage evolved current sensor 20 '. To do this, the processing unit 45 provided in the measurement unit 40 is arranged to detect an activity, by the presence of a binary signal, on the conductor 53a of the communication pair 53 possibly supporting the digital transmission in the case of an evolved current sensor 20 '. If, after a certain time, it detects no coherent activity on this conductor 53a, it attempts to identify a simple current sensor 20 as a function of the average voltage levels detected between the conductor 53a of the communication pair 53 and the driver 52- of negative polarity of the supply pair 52. If it can not match a simple current sensor 20 with the average voltage levels detected, it restarts a search for an advanced current sensor 20 ' .

When the measuring device 11-13 comprises a current sensor 20 'evolved, for example according to Figure 2, one of the two conductors 53b of the communication pair 53 is unused. It is advantageous and non-exhaustive to use this conductor 53b available to transmit a complementary analog signal that can be used by the processing unit 45 and to improve its knowledge of the environment of the current sensor 20 ', or use this conduct 53b for transmitting information to the current sensor 20 ', for example to conduct a measurement campaign by changing the nominal size of the current sensor 20' if it offers this possibility.

It is also possible to use the conductor 53b of the communication pair 53 to convey a complementary signal corresponding to an additional physical or auxiliary physical quantity of the electrical installation and for example being in an analog form. As seen with reference to FIGS. 2 to 4, this complementary signal may be an auxiliary voltage signal image of the voltage of the conductor L1 of the electrical installation whose current is measured, as allowed by the auxiliary voltage sensor. 30. This auxiliary voltage signal can be very inaccurate in amplitude since it is not used to measure the actual voltage on the conductor L1, but its shape must be close to the actual voltage signal and the time offset with the signal of real voltage must be relatively low, of the order of a few degrees of phase shift compared to the frequency of the network equal for example to 50Hz. The processing unit 45 of the measurement unit 40 may comprise a correlation module for automatically detecting which voltage path corresponds to the current sensor 20 'provided with an auxiliary voltage sensor 30, looking for which nominal voltages V1, V2, V3 connected to the processing unit 45 have the maximum correlation with the auxiliary voltage signal Vaux. FIG. 5 illustrates an example of connection between the three phases L1, L2, L3 of the electrical installation and the voltage paths V1, V2, V3 on the one hand and the current paths II, 12, 13 on the other hand. on the processing unit 45. In this case, the voltage paths V1, V2, V3 are coupled to voltage sensors 30 ', for example, in direct contact for measuring the real voltage on each of the phases. Branch inversion has been voluntarily introduced between phases L2 and L3 on voltage paths V2 and V3. The diagram of FIG. 6 shows, by way of example, the correlation between the auxiliary signal Vaux obtained by the auxiliary voltage sensor 30 and the voltage path VI corresponding to the phase L1 of the installation on which the current sensor 20 ' is installed and connected to the channel II of the processing unit 45. Of course, this correlation method can be performed automatically on the other phases L2 and L3 if the current sensors 20 'are provided with an auxiliary voltage sensor 30. In this configuration, the auxiliary signal Vaux, an image of the voltage on one of the conductors L1 on which the intensity is measured, can also be used to detect the opening of a breaking device (such as a circuit breaker). or melting a fuse to trigger an alert or the like, if the voltage sensors 30 'feeding the voltage paths V1, V2, V3 of the processing unit 45 are connected to the phases L1, L2, L3 upstream of the device cutoff and if the current sensors 20 'comprising an auxiliary voltage sensor 30 are connected downstream of said cutoff device. Possibilities of industrial application: The measuring device 10-13 according to the invention uses electrical and electronic components available on the market. It is made intelligent thanks to the integration of programmable processing units 45, 60 and to both analog and digital communication between the current sensors 20, 20 'and the measurement unit 40. As a result, the device 10-13 is versatile and adapts to any type of current sensor 20, 20 'automatically, and in the same way to any other type of equivalent sensors. This design opens up new perspectives for the exploitation of the physical quantities of an electrical installation and thus allows multiple applications tending towards a greater security and a better reliability of the measured data.

For example, in the context of an energy metering application, the use of the measuring device 10-13 according to the invention makes the fraud particularly delicate. Indeed, this measuring device 10-13 is able to detect the absence of a current sensor, the nominal size of a current sensor, the replacement of a current sensor by checking the serial number, the inconsistencies between the voltages measured directly by the measuring device 40 connected to the current sensor (s) 20, 20 ', said measuring device 40 being in fact an energy meter, and those detected by the voltage sensor auxiliary 30, etc.

Likewise, the operation of an auxiliary signal can also make it possible to improve the reliability of the search for earth faults in isolated electrical installations of the earth. In this case, the current sensor includes a ground leakage current sensor. The signal useful for measuring earth-resistive faults is in general a very low-frequency, low-amplitude current signal, which is often superimposed on a current signal present on the conductor at the frequency of the grating. higher. In order to be able to correctly process the useful signal at very low frequency, low-pass filtering of the overall signal is carried out in order to be able to correctly amplify the current signal at a very low frequency. However, the earth leakage current signal of the installation to be tested may have a component at the mains frequency (50 Hz for example) which may be of much greater amplitude than the low frequency component transmitted on the pair. 51. This frequency-related component of the network can provide interesting information, in particular for verifying the absence of saturation of the earth leakage current sensor and that the earth leakage current sensor is well used in a current range compatible with the Earth Resistive Flaw Detection Application. The conductor 53b of the communication pair 53 can therefore be used to provide the unfiltered image of the earth leakage current and to trigger an alert if necessary.

Another example of operation of an auxiliary signal may be a signal providing information on the same physical quantity as that already measured, for example a current signal, but obtained in a different and less precise manner by a good additional current sensor. walk. The comparison of the two signals representative of the same physical quantity can make it possible to detect a failure of the main current sensor 20, 20 'and thus finds its place in measuring devices 1013 for which operational safety is an important criterion. These various exemplary embodiments show perfectly the great flexibility of use of this measuring device 10-13 as well as its operating possibilities thanks in particular to the connection cable 50 connecting the current sensors 20, 20 'and the voltage sensor. auxiliary 30 to the measurement unit 40 for conveying information other than the values of the quantities measured by said sensors, this other information can be infinite and used to perform multiple functions such as anomaly detection, fraud and / or cut, control, surveillance, security, etc. The present invention is not limited to the embodiments described but extends to any modification and variation obvious to a person skilled in the art while remaining within the scope of protection defined in the appended claims.

Claims (19)

REVENDICATIONS1. Measuring device (10-13) of at least one physical quantity of an electrical installation, comprising at least one sensor (20, 20 ') arranged for measuring at least said physical quantity and delivering at least one signal representative of said quantity and at least one measurement unit (40) arranged to receive said signal and process it to output at least one usable measurement value, said sensor and said measurement unit being connected to each other by at least one connection cable (50). ), characterized in that said connecting cable (50) comprises at least three pairs of conductors, a first pair of conductors (51+, 51-), called measuring pair (51), arranged to transmit said signal representative of said physical quantity measured by said sensor (20, 20 '), a second pair of conductors (52+, 52-), called power pair (52), arranged to electrically power said sensor (20, 20') by said unit of mesu re (40), and a third pair of conductors (53a, 53b), called a communication pair (53), arranged to transmit at least one complementary signal between said sensor (20, 20 ') and said measurement unit (40) allowing at least the automatic recognition of said sensor by said measurement unit, and in that said complementary signal transmitted on at least one of the conductors (53a, 53b) of said communication pair (53) is indifferently an analog or digital signal. 2. Measuring device according to claim 1, characterized in that said sensor (20, 20 ') comprises encoding means (23, 24; 60) arranged to characterize said sensor and transmit to said measurement unit (40). via said communication pair (53) at least one complementary signal corresponding to at least one identification characteristic of said sensor enabling said measurement unit (40) to automatically recognize said sensor (20, 20 '). 3. Measuring device according to claim 2, characterized in that said sensor (20) comprises two resistors (23, 24) whose resistance values are chosen according to at least one identification characteristic of said sensor, and in that said measuring unit (40) comprises two other resistors (25, 26) arranged to form, with the two resistors (23, 24) of said sensor (20), two dividing bridges connected on the one hand to said pair of power supplies ( 52) and on the other hand to said communication pair (53) for providing at the terminals of said communication pair (53) at least one analog voltage complementary signal representative of said identification characteristic of said sensor (20). 4. Measuring device according to claim 2, characterized in that said sensor (20 ') comprises a processing unit (60) in which is recorded at least one identification characteristic of said sensor (20'), said processing unit being connected on the one hand to said power pair (52) and on the other hand to at least one of the conductors (53a) of the communication pair (53) for providing at least one complementary signal in digital form representative of said identifying feature of said sensor (20 '). Measuring device according to one of claims 2 to 4, characterized in that said encoding means (23, 24; 60) are arranged to transmit to said measurement unit (40) via said communication pair ( 53) a plurality of complementary signals corresponding to a plurality of identification characteristics of said sensor enabling said measurement unit (40) to recognize said sensor (20, 20 '). Measuring device according to claim 5, characterized in that said identification characteristics of said sensor (20, 20 ') are chosen from the group comprising the nominal voltage of the sensor, the nominal current of the sensor, the calibration data of the sensor. sensor, the gain compensation curve of the sensor, the compensation curve of the sensor phase errors. 7. Measuring device according to claim 2, characterized in that said pair of communication (53) is arranged to convey on one of its conductors (53a) at least a first complementary signal representative of at least one identification characteristic said sensor (20, 20 ') and on the other of its conductors (53b) at least a second complementary signal corresponding to an auxiliary physical quantity of said electrical installation. 8. Measuring device according to any one of the preceding claims, characterized in that said sensor (20, 20 ') is a current sensor arranged to measure the current on one of the conductors (L1) of said electrical installation. 9. Measuring device according to claim 8, characterized in that it comprises at least one auxiliary voltage sensor (30) arranged to measure an auxiliary voltage value representative of the voltage present on the conductor (L1) which is measured current by said current sensor (20, 20 '), this auxiliary voltage value forming an auxiliary physical quantity carried on one of the conductors (53b) of said communication pair (53). 10. Measuring device according to claim 9, characterized in that said auxiliary voltage sensor (30) is integrated with said current sensor (20, 20 '). 11. Measuring device according to claim 9, characterized in that said auxiliary voltage sensor (30) is connected in series between said current sensor (20, 20 ') and said measurement unit (40) and connected to each other. them by at least one connection cable (50). 12. Measuring device according to claim 11, characterized in that said auxiliary voltage sensor (30) comprises at least one selector (70) arranged to automatically invert the direction of connection of said auxiliary voltage sensor (30) between said sensor. current (20, 20 ') and said measuring unit (40) in the event of a branching error. 13. Measuring device according to claim 8, characterized in that said current sensor (20, 20 ') comprises at least one earth leakage current sensor at very low frequency with respect to the frequency of the network supplying said installation. electrical connector arranged to measure an earth leakage current value with a bandwidth including at least the frequency of the supply network, this earth leakage current value forming an auxiliary physical quantity carried on one of the conductors (53b ) of said communication pair (53). 14. Measuring device according to claim 8, characterized in that said current sensor (20, 20 ') comprises at least one temperature sensor arranged to measure the temperature of said current sensor, this temperature forming an auxiliary physical quantity conveyed on one of the conductors (53b) of said communication pair (53). 15. Measuring device according to claim 8, characterized in that said current sensor (20, 20 ') comprises at least one additional current sensor arranged to perform a second measurement of current on the conductor (L1) of said electrical installation. , this second current measurement forming a physical quantity conveyed on one of the conductors (53b) of said communication pair (53) to check the proper operation of said current sensor (20, 20 ') by comparison of this second current measurement with that performed by said current sensor (20, 20 '). Measuring device according to claim 5, characterized in that said measuring unit (40) comprises a processing unit (45) containing at least one correspondence table between identification characteristics and sensors (20, 20 '). ), and in that said processing unit (45) is connected to said communication pair (53) to receive at least the complementary signal representative of said identification characteristic enabling it to automatically recognize the sensor (20, 20 ') which is connected to said measuring unit (40) and outputting a readable correlated value of said measured physical quantity. Measuring device according to claim 9, characterized in that it comprises N current sensors (20, 20 '), each provided with an auxiliary voltage sensor (30), and N voltage sensors (30'). arranged to respectively measure the current and the voltage on N conductors (L1, L2, L3) of said electrical installation, and in that said measurement unit (40) comprises a correlation module arranged to match the voltage measurement ( V1, V2, V3) which corresponds to the measurement of the auxiliary voltage (Vaux1, Vaux2, Vaux3) performed on the same conductor (L1, L2, L3) of said electrical installation and automatically compensate for any connection errors of said sensors (20). , 20 ', 30'). 18. Use of the measuring device (10-13) according to any one of the preceding claims for detecting an attempt of fraud on said measuring device (10-13) by detecting an inconsistency on the signals transmitted via said cable of connection (50) between said sensor (20, 20 ') and said measurement unit (40). 19. Use of the measuring device (10-13) according to claim 17 for detecting the opening of a cut-off device arranged upstream of an electrical installation if on the one hand said voltage sensor (30 ') is connected. upstream of said cut-off device and if on the other hand said current sensor (20 ') provided with its auxiliary voltage sensor (30) is connected downstream of said cut-off device.